fix(tui): responsive layout for narrow screens

[vmotta8]

What does this PR do?

fixes #8938

fixes layout issues on narrow terminal screens (< 80 columns):

• permission prompt: moves action buttons and hints to a second line on narrow screens instead of being cut off
• session header: moves context info and version to a second line on narrow screens
• subagent session header: always shows navigation buttons on a separate line, and moves context info to a second line on narrow screens (3 lines total)

How did you verify your code works?

there are no tui component tests, so i tested manually by resizing terminal to various widths

permission prompt
before:

after:

session header
before:

after:

subagent session header
before:

after:

or

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

No duplicate PRs found